Oxy-fuel cutting torches discharge fuel gas and oxygen from a nozzle for cutting purposes. A typical torch includes a control body for being connected to separate fuel gas and oxygen supplies, tubes for supplying the oxygen and fuel gas from the control body to a head, and a cutting tip mounted to the head. The cutting tip receives the fuel gas and oxygen from the head and discharges these gases from its nozzle. More specifically, the head includes an interior surface extending around and defining a head cavity, an oxygen port that is open to the head cavity for supplying oxygen to the head cavity, and a fuel gas port that is open to the head cavity for supplying fuel gas to the head cavity. The cutting tip includes multiple passageways for directing the gases from the head to the nozzle.
Conventional torches first generate a preheat flame with gases discharged from the nozzle, and the preheat flame is used to heat a metal workpiece. After the preheat flame has heated the workpiece sufficiently, a high velocity cutting oxygen stream is activated and delivered through the nozzle. The high velocity cutting oxygen stream physically removes molten material of the workpiece by oxidation, to cut the workpiece. Typically, a number of valves and related components are provided upstream of the nozzle, such as in the control body, to control the operations of the cutting torch.
Flashback is a reaction caused in cutting torches by the reverse flow and ignition of the explosive mixture of gases used in the operation of the torch. Flashback typically originates at the nozzle of the torch and is often caused by an obstruction at this point, operator error, and/or improper gas pressure. Due to the rapid and explosive nature of flashback, it poses a potential hazard to the operator of the gas torch and can damage the gas torch and associated equipment. Accordingly, and as disclosed in WO 94/16270, it is known to include sintered metal in a gas torch nozzle in an effort to control flashback. Similarly, and as disclosed in U.S. Pat. No. 1,114,706, it is known to have a valve within an upper part of a gas torch nozzle in an effort to control flashback.
Although it is known to control flashback near its source, it is believed that there is a need in the art for an improved flashback arrestor that is proximate the head of a cutting torch for restricting flashback into the head, and which provides an improved balance of properties.